Implanted magnets retrieval system and method

ABSTRACT

A method of retrieving a pair of previously implanted magnets from a patient&#39;s body includes maneuvering a guide catheter, which includes a guide magnet affixed to its distal end, toward the implantation site of the implanted magnets. The guide magnet is magnetically coupled to one of the implanted magnets in an orientation in which a through hole of the guide magnet is in register with through holes of the first and second implant magnets. An elongate capture member is slid through the lumen of the guide catheter until one of a proximal segment and a distal segment extends through the through holes of the guide magnet and the implanted magnets. An abutment segment of the elongate capture member, which separates the proximal segment and the distal segment is maneuvered into contact with the magnets. Then, the abutment segment, the guide magnet and the implanted magnets are moved as a group away from the implantation site.

GOVERNMENT RIGHTS

This invention was created in the performance of a Cooperative Researchand Development Agreement with the National Institutes of Health, andAgency of the Department of Health and Human Services. The Government ofthe United States has certain rights in this invention.

TECHNICAL FIELD

The present disclosure relates generally to a retrieval system forimplanted magnets, and more particularly to a magnetic retrieval systemfor a pair of implanted magnets that define through holes in registerwith each other.

BACKGROUND

Magnetic compression and anastomosis is a strategy by which first andsecond magnets are located in respective volumes within a patient. Thetwo magnets are magnetically linked to compress the walls defining therespective volumes together. For instance, co-owned U.S. Pat. No.8,556,919 teaches a delivery system for magnet anastomosis in which thetissue compressed between a pair of implanted magnets causes a necrosisof the walls of the stomach and jejunum until an anastomosis is formed.This reference suggests that, after the anastomosis is formed, theimplanted magnets can pass through the body naturally or can be removedby strategies such as laparotic removal, or possibly an endoscopicremoval. While these strategies for removal of implanted magnets may beattractive and feasible for creating an anastomosis in the digestivesystem, these suggested retrieval strategies may not be realisticallyfeasible in other body volumes, such as creating an anastomosis betweentwo cardiovascular passageways in a patient.

The present disclosure is directed toward one or more of the problemsset forth above.

SUMMARY

In one aspect, a magnet retrieval system includes a guide catheter thatdefines a lumen and includes a guide magnet affixed to a distal end, andthe guide magnet defines a through hole in communication with the lumen.An elongate capture member is slidably received in the lumen andincludes an abutment segment separating a proximal segment from a distalsegment. A first implant magnet is magnetically coupled to a secondimplant magnet. A through hole defined by the first implant magnet is inregister with a through hole defined by the second implant magnet. Themagnet retrieval system has a retrieval configuration in which the guidemagnet is magnetically coupled to one of the first implant magnet andthe second implant magnet, and one of the proximal segment and thedistal segment of the elongate capture member extends through thethrough holes of the guide magnet, the first implant magnet and thesecond implant magnet. Also, the abutment segment is in contact with oneof the guide magnet, the first implant magnet and the second implantmagnet.

A method of retrieving previously implanted magnets from an implantationsite includes maneuvering a guide catheter toward the implantation site.The implanted magnets include a first implant magnet magneticallycoupled to a second implant magnet, and a through hole defined by thefirst implant magnet is in register with a through hole defined by thesecond implant magnet. The guide catheter defines a lumen and includes aguide magnet affixed to a distal end. The guide magnet defines a throughhole in communication with the lumen. The guide magnet is magneticallycoupled to one of the first implant magnet and the second implant magnetin an orientation in which the through hole of the guide magnet is inregister with the through holes of the first implant magnet and thesecond implant magnet. An elongate capture member is slid through thelumen until one of a proximal segment and a distal segment extendsthrough the through holes of the guide magnet, the first implant magnetand the second implant magnet. The elongate capture member includes anabutment segment that separates the proximal segment from the distalsegment. The abutment segment, the guide magnet, the first implantmagnet and the second implant magnet are moved as a group from theimplantation site while the abutment segment contacts one of the guidemagnet, the first implant magnet and the second implant magnet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial schematic view of a pair of implanted magnetspositioned at an implantation site in a patients body;

FIG. 2 is a schematic view of a guide catheter being maneuvered towardthe fear of implanted magnets of FIG. 1;

FIG. 3 is a schematic view of a guide catheter of FIG. 2 magneticallycoupled to the pair of implanted magnets at the implantation site;

FIG. 4 is a schematic view showing an elongate capture member being slidthrough the lumen of the guide catheter of FIG. 3 from one directionwhile a grasping element of a pull approaches the implantation site froman opposite direction;

FIG. 5 is a schematic view showing the grasping element coupled to adistal segment of the elongate capture member of FIG. 4;

FIG. 6 is a schematic view of the magnetic retrieval system being movedas a group by a pull from the implementation site;

FIG. 7 shows an elongate capture member according to another aspect ofthe present disclosure being slid in the lumen of the guide cathetertoward the implantation site;

FIG. 8 is a schematic view that shows the elongate capture member ofFIG. 7 with its abutment segment enlarged to contact the implantedmagnets;

FIG. 9 is a schematic view showing the magnetic retrieval system movingas a group away from the implantation site according to another aspectof this disclosure;

FIG. 10 is a schematic view of an implantation site with a second guidecatheter approaching from an opposite side of the implanted magnets;

FIG. 11 is a schematic view showing an elongate capture member beingslid through the lumens of the first and second guide catheters; and

FIG. 12 is a schematic view showing the magnetic retrieval system beingmoved as a group away from the implantation site according to anotheraspect of the present disclosure.

DETAILED DESCRIPTION

Referring initially to FIG. 1, a pair of previously implanted magnets 13are located at an implantation site 12 in a patient's body 10. Theimplanted magnets 13 may have been placed the patient's body 10 tocreate an anastomosis between two cardiovascular passageways, or thevolumes. After the implanted magnets 13 have been in the patient's body10 for a prescribed period of time, such as several weeks, there may bea desire or need to remove the implanted magnets 13 from the patient'sbody 10. This disclosure teaches a method and apparatus for retrievingthe implanted magnets 13. Depending upon which strategy is utilized, theimplanted magnets 13 may be retrieved via a single entry into thepatient, such as that first entry site 18, or may utilize two entrysites, such as second entry site 19, in order to retrieve the implantedmagnets 13. In most instances, each of the implanted magnets 13 wouldlikely have been originally positioned in the patient's body 10 via twoseparate entry sites which may have been in close proximity to first andsecond entry sites 18 and 19, or could have been located elsewherewithout departing from the scope of the present disclosure.

Referring now in addition to FIGS. 2 and 3, the previously implantedmagnets 13 include a first implant magnet 14 magnetically coupled to asecond implant magnet 16. A through hole 15 defined by the first implantmagnet 14 is in register with a through hole 17 defined by the secondimplant magnet. The first implant magnet 14 may be located in a firstvolume 21, which may be a first cardiovascular passageway, and thesecond implant magnet 16 may be located in a second volume, which may bea second and different cardiovascular passageway. Tissue 11 that definesportions of the first and second volumes 21, 22 is squeezed betweenfirst implant magnet 14 and second implant magnet 16. A method ofretrieving the previously implanted magnets 13 includes maneuvering aguide catheter 33 toward the implantation site 12 utilizing techniqueswell known in the art via first entry site 18. Guide catheter 33 definesa lumen 34 and includes a guide magnet 35 affixed to a distal end 36.The guide magnet 35 defines a through hole 37 in communication withlumen 34. The magnetic poles (S, N) of the first implant magnet 14 andthe second implant magnet 16 are arranged such that the implantedmagnets 13 naturally magnetically couple in the configuration shown sothat through holes 15 and 17 are in register. Likewise, the north andsouth poles of the guide magnet 35 are configured such that the guidemagnet 35 tends to be attracted to second guide magnet 16 tomagnetically couple in the configuration shown in FIG. 3, rather thanbeing attracted toward magnetic coupling along different surfaces. Theguide catheter 33 is maneuvered until the guide magnet 35 magneticallycouples to one of the first implant magnet 14 and the second implantmagnet 16 in an orientation in which the through hole 37 of the guidemagnet is in register with the through holes 15, 17 of the first implantmagnet 14 and the second implant magnet 16. In the illustratedembodiment, guide magnet 35 is shown magnetically coupled with secondimplant magnet 16. The portion of the procedure shown in FIGS. 2 and 3is common to the various different methods and devices illustrated inthe following Figures for retrieving the previously implanted magnets13.

Referring now in addition to FIGS. 4-6, after guide catheter 33 has beenproperly positioned with guide magnet 35 magnetically coupled to secondimplant magnet 16 as shown in FIG. 3, an elongate capture member 40 maybe slid through lumen 34 until one of a proximal segment 41 and a distalsegment 43 extends through the through holes 37, 17, 15 of the guidemagnet 35, second implant magnet 16 and first implant magnet 14,respectively. The elongate capture member 40 includes an abutmentsegment 42 that separates the proximal segment 41 from the distalsegment 43. In this embodiment, abutment segment 42 may have a crosssection 44 that is larger than the through hole 37 of guide magnet 35.Cross section 44 may be a fixed cross section. In other embodiments, theabutment segment 42 may have an expandable cross section that has a lowprofile configuration that allows abutment segment 42 to pass throughthe through holes of the guide and implanted magnets 35, 13. Dependingupon the state of the tissue 11 trapped between the first implant magnet14 and the second implant magnet 16, the distal tip of the elongatecapture member 40 may need to be sufficiently sharp to puncture throughthe necrosis. In this version, the abutment segment has a fixed shape 47and the cross section 44 is smaller than lumen 34, but larger than thethough hole 37 of guide magnet 35. In the strategy illustrated in FIGS.4-6, a pull 50, which includes a grasping element 51 may approachimplantation site 12 via passageway 21 and second entry site 19.

FIG. 5 shows a complete magnet retrieval system 30 in a retrievalconfiguration 29 in which guide magnet 35 is magnetically coupled to oneof the first implant magnet 14 and second implant magnet 16, and one ofthe proximal segment 41 and distal segment 43 of the elongate capturemember 40 extends through the through holes 37, 17, 15 of the guidemagnet 35, second implant magnet 16 and first implant magnet 14,respectively. Finally, the retrieval configuration 29 includes theabutment segment 42 in contact with one of the guide magnet 35, thefirst implant magnet 14 and the second implant magnet 16. In thisembodiment, the abutment segment 42 is in contact with the guide magnet35 as shown in FIG. 5. After achieving the retrieval configuration 29,the abutment segment 42, the guide magnet 35, the first implant magnet14 and the second implant magnet 16 are moved as a group 75 from theimplantation site 12 under the action of pull 50 pulling elongatecapture member 40 toward the second entry site 19 through which pull 50gained access to the patient's body 10. Moving the group 75, whichincludes abutment segment 42, guide magnet 35, second implant magnet 17and first implant magnet 15, is accomplished by moving the pull 50 awayfrom the implantation site 12. In the illustration, grasping element 51is shown as a snare, but those skilled in the art will appreciate thatnumerous other structures could be substituted, including but notlimited to a grasping element in the form of forceps, or possibly even astrategy in which distal segment 43 is received in a wire mesh that ispinched together as a grasping element to capture distal segment 43 ofelongate capture member 40. Those skilled in the art will appreciatethat guide catheter 33 follows with guide magnet 35 as pull 50 pulls theentire assembly out of the patient's body 10 through second entry site19 leaving a passage 20 between the first volume 21 and the secondvolume 22 of the patient's cardiovascular system. When this occurs, atissue fragment 24, which was squeezed between first implant magnet 14and second implant magnet 16 may detach and be carried away with group75. After the proximal segment 41 of elongate capture member 40 and theentire guide catheter 33 exit the patient's body 10, the procedureaccording to one aspect is completed.

Those skilled in the art will appreciate that the edges of tissue 11adjacent the pair of implant magnets 13 may grow together over timewhile the implanted magnets were positioned in the patient's body sothat the tissue 11 itself defines passage 20 possibly without the needfor any artificial support or other permanent device. Also shown inFIGS. 5 and 6 on the right hand side are an optional second guidecatheter 60 and/or an optional outer catheter 58 that may be utilized inthe procedure in a manner described infra.

Referring now to FIGS. 7-9, an alternative retrieval process utilizes anelongate capture member 140 with an abutment segment 142 that has anexpandable cross section 144. Like the earlier embodiment, elongatecapture member 140 includes a proximal segment 141 separated from adistal segment 143 by abutment segment 42. The expandable cross section144 has a first configuration 145 in which the expandable cross section144 is smaller than the through holes 37, 17, 15 of guide magnet 35,second implant magnet 17 and first implant magnet 14, respectively. Theexpandable cross section 144 may be changed to a second configuration146 as shown in FIG. 8 in which the expandable cross section 144 islarger than the through holes 37, 17, 15 of the guide magnet 35, thesecond implant magnet 16 and the first implant magnet 14. Those skilledin the art will appreciate that FIGS. 7-9 were preceded by the stepsshown in FIGS. 2 and 3. Although not necessary, the elongate capturemember 140 may take the form of a malecot that may utilize an actuatorpin 148 to change expandable cross section 144 between the firstconfiguration 145 and the second configuration 146. Those skilled in theart will appreciate that a wide variety of devices are known that couldbe utilized as an elongate capture member 140 with an abutment segment142 that has an expandable cross section 144 that differ in structureand shape from the malecot type device shown, and those alternativedevices would also fall within the intended scope of the presentdisclosure. The distal segment 141 is moved through the through holes37, 17, 15 of the guide magnet 35, second implant magnet 16 and firstimplant magnet 14, respectively. After the distal segment has passedthrough the through holes 37, 17, 15, the abutment segment 142 is passedthrough the through holes 37, 17 and 15 while the expandable crosssection 144 is in the first configuration 145. The expandable crosssection 144 is then changed from the first configuration 145 to thesecond configuration 146. Thereafter the abutment segment 142 is movedinto contact with the first implant magnet 14. The important aspect inthis regard is that the expandable cross section can be maneuveredthrough the through holes 37, 17, 15 in the small diameter firstconfiguration 145, but cannot be maneuvered through the through holes37, 17, 15 in the large diameter second configuration 146 so that thegroup 75 can be moved together as shown in FIG. 9 in the reversedirection with the elongate capture member 140. The group includes theabutment segment 142, the guide magnet 35, the second implant magnet 16and the first implant magnet 14 in a reverse direction and out of thepatient's body 10 through the first entry site 18. Thus, the procedureand device illustrated in FIGS. 7-9 allows the previously implantedmagnets 13 to be removed from the patient's body 10 utilizing only asingle entry site 18. Like the previous strategy, the removal of themagnetic magnet retrieval system 130 leaves a passage 20 between thefirst volume 21 and the second volume 22.

Referring now to FIGS. 10, 11 and 12, still another strategy forretrieving a pair of implanted magnets 13 from an implantation site 12is shown. The steps shown in FIGS. 10-12 are immediately preceded by thepreviously described steps of FIGS. 2 and 3. After the guide magnet 35of the first guide catheter is magnetically coupled to the secondimplant magnet 16, a second guide catheter 60 is maneuvered towardimplantation site 12 via second entry site 19 (FIG. 1). Like the firstguide catheter 33, second guide catheter 60 defines a lumen 61 andincludes a second guide magnet 62 affixed to a distal end 63. The secondguide magnet 62 defines a through hole 64 in register with the lumen 61.The second guide magnet 62 is magnetically coupled with one of the firstimplant magnet 14 and second implant magnet 16 as shown in FIG. 11 in anorientation in which the through hole 64 of the second guide magnet 62is in register with the through holes 15, 17 of the first implant magnet14 and the second implant magnet 16. Thereafter, an elongate capturemember 240 is moved through lumen 34 so that distal segment 243 movesthrough the through holes 37, 17, 15, 64 and into lumen 61. Thisstrategy is similar to the strategy shown with relation to FIGS. 4-6,except that the distal segment 243 of the elongate capture member 240 issufficiently long that a distal portion of distal segment 243 exits thepatient's body 10 through second entry site 19 before abutment segment242 comes into contact with guide magnet 35. This allows for thepotential elimination of a separate pull 50 as shown in the earlierembodiment. Instead, the user may simply grasp the distal segment 243(now functioning as a pull) of the elongate capture member 240 and pullthe entire magnet retrieval system 230, which includes the group 75 outof the patient's body through second entry site 19. The second guidecatheter 60 ensures that no steering is needed when advancing the distalsegment 243 of elongate capture member 240 from first access site 18through the implanted magnets 13 and out of the second access site 19.Like the earlier embodiments, elongate capture member 240 includes aproximal segment 241 separated from a distal segment 243 by an abutmentsegment 242, which is illustrated in this embodiment as being a fixedcross section that is larger than the through holes 37, 64 of the guidemagnets 35, 62 and the through holes 17, 15 of the implanted magnets 13.

In the event that there is some concern that the implanted magnets 13will have difficulty detaching from the tissue 11, an optional outercatheter 58 may be utilized. In particular, in the embodiment shown inFIGS. 10-12, an optional outer catheter 58 is shown in FIG. 12. Theouter catheter 58 may be slid along the outer surface of second guidecatheter 60 after it has become magnetically coupled to the implantedmagnets 13. Detaching the first implant magnet 14 and the second implantmagnet 16 from tissue 11 at implantation site 12 may be assisted bypositioning outer catheter 58 in contact with tissue 11 in opposition toa force 76 of the abutment segment 242 onto the guide magnet 35. Asshown, outer catheter 58 defines a lumen 59 sized to receive both firstguide catheter 33 and second guide catheter 60, as well as the first andsecond implant magnets 14, 16. In this optional variation, the entiremagnet retrieval system 230 is slid out of the patient's body 10 alonglumen 59 of outer catheter 58 and eventually out of second access site19. This is accomplished, the outer catheter 58 may also be withdrawnout of the patients body 10 through second access site 19 to completethe procedure.

Returning briefly to FIG. 9, an optional outer catheter 58 is shown indashed lines in order to contact and hold tissue 11 in place when themagnetic retrieval assembly 130 is detached from tissue 11. In thisexample, the magnetic retrieval system 130 is slid through lumen 59 andout of the patient's body 10 through first access site 18.

Referring back to again to FIGS. 5 and 6, dotted lines show an optionaluse of a second guide catheter 60 and/or an outer catheter 58. By usinga second guide catheter 60, the coupling of the grasping device 51 ofpull 50 may be more easily accomplished. The outer catheter 58 may beuseful in holding tissue 11 in place while the first implant magnet 14and the second implant magnet 16 are detached from implantation site 12responsive to movement of pull 50 and elongate capture member 40.

Referring briefly again to FIG. 5, magnet retrieval system 30 may have apre-retrieval configuration 28 in which the outer catheter 58 and theabutment segment 42 are located on opposite sides 70 of a plane 71separating the first implant magnet 14 and the second implant magnet 16.As stated earlier, the outer catheter 58 is sized to receive the firstguide catheter 33, the second guide catheter 60, if used, the firstimplant magnet 14 and the second implant magnet 16. In the embodimentsshown in FIGS. 4-6 and 10-12, the elongate capture member 40, 240 ismoved in a same direction 77 during both the sliding steps illustratedin FIGS. 4 and 11 as the step in which the abutment segment 42, 242 ismoved away from implantation site 12. This is to be contrasted with theembodiment shown in FIGS. 7-9 in which the elongate capture member 140is moved in opposite directions during sliding and abutment movingsteps.

INDUSTRIAL APPLICABILITY

The present disclosure finds general applicability to strategies forretrieving previously implanted magnets in a patient's body. The presentdisclosure finds specific applicability to retrieving previouslyimplanted magnets 13 from the cardiovascular system of a patient, butmay also have applicability in retrieving magnets from other passagewaysor volumes within a patient's body 10. Finally, the present disclosurefinds specific applicability to retrieving implanted magnets 13 in whichthe first implanted magnet 14 and the second implanted magnet 16 includethrough holes 15, 17 that are in register at the implantation site 12.

Although the present disclosure has been illustrated, in one aspect, asusing a grasping element 51 in the form of a snare with pull 50, thoseskilled in the art will appreciate that a wide variety of otherinstruments are known in the art for grasping and holding a distalsegment of a catheter-like member as shown, and all of those variousdevices are considered to fall within the scope of the presentdisclosure. In addition, another version of the strategy describedteaches an elongate capture member 140 with an expandable cross section144 illustrated in the form of a malecot that is actuated with anactuator pin 148. Nevertheless, those skilled in the art will appreciatethat other devices are well known in the art that have the ability toenlarge a segment of cross section between a diameter that could passthrough the through holes 15, 17 of the implanted magnets 13 and then beenlarged and be unable to pass back through the same through holes 15,17 so that the elongate capture member can function as a pull toretrieve the implanted magnets 13 as best shown in FIGS. 7-9. Any of thewide variety of devices that have an expandable cross section capabilitywould also fall within the scope of the present disclosure.

It should be understood that the above description is intended forillustrative purposes only, and is not intended to limit the scope ofthe present disclosure in any way. Thus, those skilled in the art willappreciate that other aspects of the disclosure can be obtained from astudy of the drawings, the disclosure and the appended claims.

What is claimed is:
 1. A method of retrieving previously implantedmagnets from an implantation site, the implanted magnets include a firstimplant magnet magnetically coupled to a second implant magnet, and athrough hole defined by the first implant magnet being in register witha through hole defined by the second implant magnet, the methodcomprising the steps of: maneuvering a guide catheter toward theimplantation site, and the guide catheter defines a lumen and includes aguide magnet affixed to a distal end, and the guide magnet defining athrough hole in communication with the lumen; magnetically coupling theguide magnet to one of the first implant magnet and the second implantmagnet in an orientation in which the through hole of the guide magnetis in register with the through holes of the first implant magnet andthe second implant magnet; sliding an elongate capture member throughthe lumen until one of a proximal segment and a distal segment extendsthrough the through holes of the guide magnet, the first implant magnetand the second implant magnet, and wherein the elongate capture memberincludes an abutment segment that separates the proximal segment fromthe distal segment; and moving the abutment segment, the guide magnet,the first implant magnet and the second implant magnet as a group fromthe implantation site while the abutment segment contacts one of theguide magnet, the first implant magnet and the second implant magnet. 2.The method of claim 1 wherein the distal segment of the elongate capturemember extends through the through holes of the guide magnet, the firstimplant magnet and the second implant magnet; coupling a graspingelement of a pull to the distal segment of the elongate capture member;and the step of moving the abutment segment includes moving the pullaway from the implantation site.
 3. The method of claim 1 wherein themoving step includes detaching the first implant magnet and the secondimplant magnet from tissue at the implantation site by positioning anouter catheter in contact with the tissue in opposition to a force ofthe abutment segment onto the one of the guide magnet, the first implantmagnet and the second implant magnet.
 4. The method of claim 1 whereinthe abutment segment includes an expandable cross section that has afirst configuration in which the expandable cross section is smallerthan the through holes of the guide magnet, the first implant magnet andthe second implant magnet, and a second configuration in which theexpandable cross section is larger than the through holes of the guidemagnet, the first implant magnet and the second implant magnet; thesliding step includes moving the proximal segment through the throughholes of the guide magnet, the first implant magnet and the secondimplant magnet, then sliding the abutment segment through the throughholes of the guide magnet, the first implant magnet and the secondimplant magnet while the expandable cross section is in the firstconfiguration; changing the expandable cross section from the firstconfiguration to the second configuration; and moving the abutmentsegment into contact with one of the first implant magnet and the secondimplant magnet.
 5. The method of claim 1 wherein the guide catheter is afirst guide catheter, and the guide magnet is a first guide magnet;maneuvering a second guide catheter toward the implantation site, andthe second guide catheter defines a lumen and includes a second guidemagnet affixed to a distal end, and the second guide magnet defining athrough hole in register with the lumen; magnetically coupling thesecond guide magnet to an other one of the first implant magnet and thesecond implant magnet in an orientation in which the through hole of thesecond guide magnet is in register with the through holes of the firstimplant magnet and the second implant magnet; and the step of moving theabutment segment includes moving the abutment segment, the first guidemagnet, the first implant magnet, the second implant magnet and thesecond guide magnet as a group away from the implantation site.
 6. Themethod of claim 1 wherein the moving step includes detaching the firstimplant magnet and the second implant magnet from tissue at theimplantation site by positioning an outer catheter in contact with thetissue in opposition to a force of the abutment segment onto the one ofthe guide magnet, the first implant magnet and the second implantmagnet; wherein the abutment segment includes an expandable crosssection that has a first configuration in which the expandable crosssection is smaller than the through holes of the guide magnet, the firstimplant magnet and the second implant magnet, and a second configurationin which the expandable cross section is larger than the through holesof the guide magnet, the first implant magnet and the second implantmagnet; the sliding step includes moving the proximal segment throughthe through holes of the guide magnet, the first implant magnet and thesecond implant magnet, then sliding the abutment segment through thethrough holes of the guide magnet, the first implant magnet and thesecond implant magnet while the expandable cross section is in the firstconfiguration; changing the expandable cross section from the firstconfiguration to the second configuration; and moving the abutmentsegment into contact with one of the first implant magnet and the secondimplant magnet.
 7. The method of claim 1 wherein the guide catheter is afirst guide catheter, and the guide magnet is a first guide magnet;maneuvering a second guide catheter toward the implantation site, andthe second guide catheter defines a lumen and includes a second guidemagnet affixed to a distal end, and the second guide magnet defining athrough hole in communication with the lumen; magnetically coupling thesecond guide magnet to an other one of the first implant magnet and thesecond implant magnet in an orientation in which the through hole of thesecond guide magnet is in register with the through holes of the firstimplant magnet and the second implant magnet; the step of moving theabutment segment includes moving the abutment segment, the first guidemagnet, the first implant magnet, the second implant magnet and thesecond guide magnet as a group away from the implantation; wherein thedistal segment of the elongate capture member extends through thethrough holes of the guide magnet, the first implant magnet and thesecond implant magnet; coupling a grasping element of a pull to thedistal segment of the elongate capture member; and the step of movingthe abutment segment includes moving the pull away from the implantationsite.
 8. The method of claim 7 wherein the moving step includesdetaching the first implant magnet and the second implant magnet fromtissue at the implantation site by positioning an outer catheter incontact with the tissue in opposition to a force of the abutment segmentonto the one of the guide magnet, the first implant magnet and thesecond implant magnet.
 9. The method of claim 1 wherein the elongatecapture member is moved in a same direction during the sliding step andthe step of moving the abutment segment.
 10. A method of retrievingpreviously implanted magnets from an implantation site, the implantedmagnets include a first implant magnet magnetically coupled to a secondimplant magnet, and a through hole defined by the first implant magnetbeing in register with a through hole defined by the second implantmagnet, the method comprising the steps of: sliding an elongate capturemember through the through holes of the first implant magnet and thesecond implant magnet, and wherein the elongate capture member includesan abutment segment that separates a proximal segment from a distalsegment; and moving the abutment segment, the first implant magnet andthe second implant magnet as a group from the implantation site.
 11. Themethod of claim 10 wherein the moving step is performed while theabutment segment contacts one of the first implant magnet and the secondimplant magnet.
 12. The method of claim 10 wherein the elongate capturemember is guided during the sliding step by a guide magnet that definesa through hole; and magnetically coupling the guide magnet to one of thefirst implant magnet and the second implant magnet in an orientation inwhich the through hole of the guide magnet is in register with thethrough holes of the first implant magnet and the second implant magnet.13. The method of claim 12 including a step of maneuvering a guidecatheter toward the implantation site, and the guide catheter defines alumen and includes the guide magnet affixed to a distal end, and thethrough hole of the guide being in communication with the lumen.
 14. Themethod of claim 13 wherein the sliding step includes moving the elongatecapture member through the lumen until one of the proximal segment andthe distal segment extends through the through holes of the guidemagnet, the first implant magnet and the second implant magnet.
 15. Themethod of claim 14 wherein the step of moving the abutment segment isperformed while the abutment segment is in contact with the guidemagnet.
 16. The method of claim 10 wherein the moving step includesdetaching the first implant magnet and the second implant magnet fromtissue at the implantation site by positioning an outer catheter incontact with the tissue in opposition to a force of the abutment segmentonto the first implant magnet and the second implant magnet.
 17. Themethod of claim 10 wherein the elongate capture member is moved in asame direction during the sliding step and the step of moving theabutment segment.
 18. The method of claim 10 wherein the elongatecapture member is moved in opposite directions during the sliding stepand the step of moving the abutment segment.
 19. The method of claim 10wherein the abutment segment is changeable from a first configurationthat is smaller than the through holes of the first implant magnet andthe second implant magnet, and a second configuration in which theabutment segment is larger than the through holes of the first implantmagnet and the second implant magnet; wherein the sliding step isperformed when the abutment segment is in the first configuration; andwherein the moving step is performed when the abutment segment is in thesecond configuration.